Content-based networks are described in A Carzaniga, M. J. Rutherford, A. L. Wolf, A routing scheme for content-based networking, Department of Computer Science, University of Colorado, June 2003, the contents of which are incorporated herein by reference.
In content routed networks, a publish/subscribe data communication is provided; wherein publishers can inject content into the network, and subscribers can subscribe to content from the network. The publishers and subscribers do not require knowledge of each other.
FIG. 1 depicts an example content-routed network 1, which consists of a plurality of content routers 2, 3, 4, and 5 interconnected by links 11, 12, 15 and 16; a publisher 6 (note that a content routed network typically will have a plurality of publishers but only one is shown in FIG. 1); a plurality of subscribers 7, 8, 9 and 17 (note that a content routed network can contain a large number of subscribers, i.e. millions). A publisher is a computer or user that can insert content into the network. A subscriber is a computer or user who has expressed interest in some specific content. Publisher 6 publishes a document into the content routed network by sending it over link 10 to content router 2. Content router 2 matches the content of the received document against the subscriptions for the network, which the router learned of through a content routing protocol (refer to co-filed application Ser. No. 11/012,113, the contents of which are incorporated herein by reference) or by some other means. Content router 2 determines that the document is required by a local subscriber on content router 2, and one or more subscribers on content router 3 and content router 4, but not by any subscribers on content router 5. As a result, a single copy of the document is sent over link 11 to content router 3, since link 11 is the preferred path to content routers 3 and 4 in this example. In addition, a copy of the document is sent over link 18 to local subscriber 17. Content router 3 delivers the document to all local subscribers which have matching subscriptions, which in this case is subscriber 7. So, a copy of the document is sent over link 13 to subscriber 7. In addition, the document is forwarded on to content router 4 over link 12. In a similar manner, content router 4 delivers the document to any local subscribers with matching subscriptions, which in this case is subscriber 8. Thus, the document is sent over link 14 to subscriber 8. Content router 4 also determines that no further content routers require a copy of the document. For full details of the content routing protocol-used, reference is made to U.S. patent application Ser. No. 11/012,113.
When content routing techniques are applied to the wide area network, such as being deployed in a service provider network, new capabilities are required as opposed to deployment scenarios within an enterprise (known as an Enterprise Service Bus; ESB). A service provider, such as a regional, national or international telecommunication provider, can provide network-resident content routing capability to provide an Extended Enterprise Service Bus (EESB). Such a deployment introduces new requirements onto the content-routed network, such as the requirement to provide data logging facilities for the purpose of billing, performance monitoring, troubleshooting, and security logging. Note also that data collection is also useful for content routing within an enterprise, for example, to be able to bill various departments of the enterprise based on network usage, or to troubleshoot problems, etc.